Abstract View
Comprehensive Measurements of Organic Carbon over Long Oxidation Timescales
LESLY FRANCO DELOYA, Jesse Kroll, MIT
Abstract Number: 680
Working Group: Aerosol Chemistry
Abstract
Nonmethane organic carbon makes up a large fraction of reactive species in the atmosphere, yet most studies have only examined early generation oxidation products. Understanding the multigenerational chemical evolution of gas-phase mechanisms can help in better understanding the dynamic partitioning between the gas- and particle-phase of organic carbon, especially on multiday to multiweek scales. By using OH concentrations thousands of times higher than that of the atmosphere, we can simulate longer timescales of atmospheric aging and measure the multigenerational evolution of both gas- and particle-phase oxidation products. The OH oxidation of α-pinene under low NOx conditions is used as a model system. Gas-phase measurements were made using a PTR3 in H3O+ and NH4+ mode, and particle-phase measurements were made using an AMS and SMPS, enabling reasonably comprehensive measurements of the entire reaction product mixture. The gas-phase results are compared to predictions by the Master Chemical Mechanism (MCM), and discrepancies between models and observations are examined. Such comparisons provide an important test of our understanding of the lifecycle of reactive organic carbon in the atmosphere.